Ingenieurwissenschaften und zugeordnete Tätigkeiten
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- 2014 (32) (entfernen)
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- AC weld pool support (2)
- Electron backscatter diffraction (2)
- Graphene (2)
- Kikuchi pattern (2)
- Wasserstoff (2)
- Welding of aluminum (2)
- Welding of thick metal plates (2)
- 3D FE-simulation (1)
- AC magnetic fields (1)
- Additive manufacturing (1)
Eingeladener Vortrag
- nein (8)
The influence of two different weld imperfections (gap/crack) on the fatigue behaviour of spot welded joints was tested
Surface cracks havenoinfluenceon thefatiguelife
Samples with cracks in the electrode indentation /HAZ where tested
Stiffness curves are not significantly influenced by surface cracks
3D FE-Simulation demonstrate no changes of stress due to surface imperfections
Mechanische Eigenschaften der laserhybridgeschweißten Schweißverbindungen von hochfesten niedriglegierten Stählen erfüllen die Anforderungen der geltenden Normen
Eindringtiefe des Zusatzwerkstoff bis ca. 12 mm
Halborbitales Schweißen an 36” Rohren mit einer Wandstärke von 16 mm bei einer Schweißgeschwindigkeit von bis zu 2,2 m/min und Laserleistung von 19 kW technisch möglich
Rissfreie Schweißverbindungen an Präzisionsrohren können durch eine geeignete Schweißparameterauswahl mittels Laser-Hybridverfahren hergestellt werden
In dem Vortrag werden aktuelle Entwicklungen zum thermo-mechanischen Ermüdungsversuch aufgezeigt. In der Vergangenheit wurden ausschließlich dehnungsgeregelte TMF-Versuche durchgeführt. Zukünftig werden auch spannungsgeregelte TMF-Versuche eine Rolle spielen, besonders bei kleinen Belastungen und hohen Schwingspielzahlen. Daneben werden Rissfortschrittsmessungen bei TMF-Beanspruchung eine zunehmende Bedeutung zugemessen. Die Versuchstechnik hierzu ist noch nicht sehr verbreitet verfügbar und ist sehr anspruchsvoll. Es wird das Europäische Forschungsprojekt TEACH vorgestellt, welches beantragt, aber noch nicht bewilligt ist. Ferner wird der 3rd TMF-Workshop 2016 angekündigt, der bei der BAM in Berlin stattfinden wird.
Optical and scanning electron microscopy, as well as electron microprobe analysis and electron backscatter diffraction, have been used to study diffusion processes that occur in a diffusion pair that consistsof a single-crystal CMSX-10 nickel-base superalloy and polycrystalline nickel, at temperatures of 1050–1250°C. It has been found that, in this system, the distributions of γ-stabilizing elements (Cr, Co, W, and Re) are described by the Boltzmann solution for diffusion between two semiinfinite plates of a binary alloy. The processing of these distributions has shown that the diffusion coefficients of Cr, Co, W, and Re in the multicomponent system are close to those in binary alloys of these elements with Ni. The diffusion redistribution of the elements leads to the dissolution of the γ′ phase in the nickel-base superalloy, growth of nickel grains toward the superalloy constituent of the diffusion pair, and the formation of porosity on both sides of the migrating interface, which is determined from a crystal misorientation of the alloy single crystal and nickel grains.
Computational Advances
(2014)
Fibre Reinforced Plastics (e.g. CFRP, GFRP) characteristically show nonlinear stress-strain behaviour due to intralaminar shear loading. The determination of the in-plane shear stiffness and strength for this class of material is difficult and common test standards and methods of analysis are partially inaccurate. The identification of the in-plane shear properties was made with an especial designed “picture frame test device” which enables shear loading up to 950N/mm. Therefore the strength limit can be reached at specimens with adequate thickness and a high safety factor against buckling. Due to the chosen design the maximum of the shear loading and the final failure occur in the centre of the specimen. The experiments match with the numerical analysis.
The one-phase methods described in Chapter 2 were shown to be able to predict casting to some extent, but could not depict segregation, sedimentation and blockage occurring during flow. On the other hand, the distinct element methods described in Chapter 3 did not take into account the presence of two phases in the system and describes concrete as distinct elements interacting through more or less complex laws. A reliable numerical model of a multiphase material behaviour shall take into account both phases (solid and liquid). From the numerical point of view, concrete flow shall be seen therefore as the free surface flow of a highly-concentrated suspension of rigid grains.
The roles of microalloying niobium, titanium and vanadium for controlling austenite grain growth, microstructure evolution and hardness were investigated at different simulated heat affected zones (HAZ) for high strength low alloy (HSLA) S690QL steel. High resolution FEG-SEM has been used to characterize fine bainitic ferrite, martensite and nanosized second phases at simulated coarse and fine grain HAZs. It was found that for Ti bearing steel (Ti/N ratio is 2) austenite grain had the slowest growth rate due to the presence of most stable TiN. The fine cuboidal particles promoted intragranular acicular ferrite (IGF) formation. Nb bearing steel exhibited relatively weaker grain growth retardation compared with titanium bearing steels and a mixed microstructure of bainite and martensite was present for all simulated HAZs. IGF existed at coarse grain HAZ of Ti+V bearing steel but it was totally replaced by bainite at fine grain HAZs. Hardness result was closely related to the morphology of bainitic ferrite, intragranular ferrite and second phases within ferrite. The microstructure and hardness results of different simulated HAZs were in good agreement with welded experimental results.